The present invention was made for the purpose of constructing a tube element, especially for exhaust systems and exhaust gas recirculation systems of combustion engines in vehicles. This element consist of a single or multi-ply tube element made of metal which is equipped with cylindrical end fittings and at least two annularly corrugated bellows and a connecting pipe forming a single element, with the pipe corresponding with the bellows in diameter as well as in wall thickness, and with the inside diameter of the connecting pipe corresponding substantially with the free inside diameter of the adjacent bellows.
Such a tube element is used as a universal expansion joint within the pipe system into which it is installed due to its capability of compensating interacting lateral movements as well as angular movements and axial movements of the individual sections which are connected by the tube element. Usually, this tube element is made of metal, perhaps stainless steel, especially for use in automotive engine manufacturing. Tube elements made of non-metal material, especially of an appropriate type of plastic material, are a potential alternative for other applications.
As mentioned before, the tube element can be made of single-ply material. Depending on the individual circumstances, multi-ply material could be an alternative to increase the flexibility of the bellows, or layers of different materials may be used because of their resistance to certain stress factors such as chemical, thermal or mechanical stress.
In the traditional versions of such a tube element, the connecting pipe, which is connected with the bellows e.g. by welding, consists of material whose wall thickness is higher than that of the bellows, so that the connecting pipe is able to resist the stress to which it is subject. Due to the resulting weight of the connecting pipe and the relatively soft material of the connected bellows, this pipe will act as a vibrating element which is to be adapted to the individual application by very expensive measures, using solid compensating elements. Furthermore, the weld seams will increase both the manufacturing costs and the weight of the element.
As an attempt to avoid these problems, bellows with intermediate plain sections, i.e. single-element parts, were used. This object, however, caused the problem of a low mechanical resistance which is insufficient for many applications.